1. Field
The current invention relates to wireless communications networks. More particularly, the present invention relates to a novel and improved method of monitoring the transmission quality of wireless communications channels.
2. Background
Monitoring the transmission quality of communication channels in wireless communications networks is necessary for system operation. System operation and performance cannot be maintained without accurate real time transmission quality feedback information.
Transmission quality is measured in terms of Bit Error Rate (BER). In telecommunication transmissions, the bit error rate is the percentage of bits that have errors relative to the total number of bits received in a transmission. The BER is usually expressed as a percentage. For example, a transmission might have a BER of 4%, meaning that, out of 100 bits transmitted, 4 bits were received in error.
Presently, there is no ideal method of monitoring transmission quality in wireless communications systems. Known methods of monitoring involve adding information to the transmitted signal solely for monitoring purposes. One such method of monitoring transmission quality is accomplished by inserting a known bit pattern into the transmitted signal, and comparing the received bit pattern with the actual pattern transmitted, to calculate the BER. Another current method adds Cyclic Redundancy Code (CRC) to the transmitted signal. Cyclic redundancy checking is a method of checking for errors in data that has been transmitted on a communications link. A sending device applies a 16-bit or 32-bit polynomial to a block of data that is to be transmitted and appends the resulting CRC to the block. The receiving end applies the same polynomial to the data and compares its result with the result appended by the sender. If the CRCs agree, the data has been received without error.
Any transmission quality monitoring method which adds known bit patterns or CRC bits to the transmitted signal reduces the traffic flow throughput of the channel. Additionally, CRCs only indicate the presence of block errors, not a true measure of the BER.